In recent years, technology advances have been made in many types of display devices, including light emitting diodes (LED), organic light emitting diodes (OLED), Plasma display panels (PDP) and liquid crystal display panels (LCD).
FIG. 1 is a diagram illustrating the structure of a liquid crystal display panel. Referring to FIG. 1, the liquid crystal display panel includes a first substrate 101 and a second substrate 102 opposite to the first substrate 101, and a liquid crystal layer 103 between the first substrate 101 and the second substrate 102. Metal lines 104 (e.g., data lines or gate lines) are on the second substrate 102. A surface of the first substrate distal to the second substrate is the light emitting surface of the liquid crystal display panel. When ambient light shines on the display panel, a portion of ambient light is reflected by the first substrate 101, and a portion of ambient light transmits into the display panel through the first substrate 101. Inside the display panel, some transmitted ambient light is reflected by the surface of metal lines 104. The reflected light then exits the display panel through the first substrate 101, lowering the contrast of the display image.